Democrats are getting ready for a brutal primary in one of the biggest races of 2016 - and Republicans are elated

One candidate competing for the Democratic nomination in Florida's US Senate race is a prolific fundraiser whose relatively centrist views have made him a favorite with the party establishment.

The other is an outspoken, colorful, unabashed liberal who brags that his supporters would be willing to "crawl naked over hot coals" to vote for him.

The contrast will shape what will likely be one of the nastiest primaries of the 2016 election cycle. US Rep. Patrick Murphy (D-Florida), the more moderate candidate, is facing off against Rep. Alan Grayson (D-Florida), who entered the race this week.

"There is enormous enthusiasm for this candidacy," Grayson told Business Insider in a phone conversation on Thursday. "Voters will crawl naked over hot coals to vote for me. And that's something that no other candidate in either party can say."

Democrats had hoped to avoid such a scenario. Murphy entered the race early, and the Democratic Senatorial Campaign Committee quickly threw its support behind him - a move that was widely viewed as a hint for Grayson to stay away. When Grayson entered the race on Thursday, the DSCC issued a statement praising Murphy without mentioning Grayson's name.

Democrats hoped that Murphy would be able to sail along while attention would be focused on what one Democratic operative says is shaping up to be a "bloody" Republican primary itself. Florida is a key pickup opportunity for Democrats, as US Sen. Marco Rubio (R-Florida) opted to run for president instead of re-election.

Instead, Democrats might be even more openly combative - and Republicans are giddy.

"Grayson is actually far more reflective of today's Democratic base vote than he's given credit for, which explains why so many are apparently willing to crawl over hot coals naked for him. The joint Sanders/Grayson events in Florida will be something," one national Republican operative told Business Insider, referring to Democratic presidential candidate and US Sen. Bernie Sanders (I-Vermont).

Grayson has made no qualms about bludgeoning his opponent in public. He calls Murphy a closet Republican. In fairness, he was a registered Republican - even donating $2,300 to Mitt Romney's 2008 campaign - until months before he announced his 2012 campaign for Congress.

Democrats are still confident that Murphy will be the nominee.

"He is running a strong campaign that's focused on Florida, and we are confident that he will make a terrific Senator for the Sunshine State which is why he endorsed him," DSCC communications director Justin Barasky said in a statement Thursday.

The two have disagreements big and small on a host of issues that will be fundamental to deciding the primary - Wall Street regulations, the Affordable Care Act, healthcare, the Keystone XL Pipeline, student loans, and more.

"If you go to ProgressivePunch.org, if you go to the National Journal's website, you'll find that Patrick votes with Republicans sometimes twice as often as he votes with the Democrats," Grayson told Business Insider. "There certainly are fundamental differences on the issues."

Grayson is already touting a poll released this week by Gravis Marketing that shows him up more than 40 points on Murphy. That gave him about as big a lead over Murphy as Democratic presidential front-runner Hillary Clinton has among Florida Democrats in the poll.

He also told Business Insider that he's encouraged about his fundraising. He said when he emailed supporters on July 1, telling them that he was thinking about running, he received $100,000 in donations within 24 hours.

"Our model is the Barack Obama model," Grayson said.

Murphy has posted impressive fundraising numbers himself. This week, his campaign announced that it had raised $1.4 million in the second quarter, giving it $2.5 million cash on hand.

Political strategists and analysts say where the race could get most brutal is if and when Grayson's personal baggage comes into focus. Grayson has been going through a highly public divorce. In one interview, he referred to his estranged wife as a "gold-digger."

Grayson has also been the target of a recent House of Representatives ethics investigation over rules meant to prevent elected representatives from using their names for financial gain. One Murphy supporter has filed an ethics complaint that, among other things, accuses him of violating ethics rules when he named the investment funds after himself.

For his part, Grayson calls the ethics investigation part of a "smear campaign."

"I'm 57 years old," Grayson said. "I never had any ethics complaints filed against me until two days - two days - before declaring for the Senate. I think that voters can well understand exactly what's going on here. They can connect those dots. It's nonsensical, it's frivolous, and it's a pity."

Republicans will be dealing with quite the crowd on their own side - US Rep. Ron DeSantis and Lt. Gov. Carlos Lopez-Cantera are running, and Rep. Jeff Miller, the chair of the House Veterans Affairs Committee, looks set to enter the race.

But they hope Grayson's entry will, at minimum, force Murphy to spend heavily to fend off the primary fight. And maybe make it a bit more fun, too.

"It takes what originally promised to be a dull and dry Senate race and turns it into a race that may make Florida Man himself blush," said one veteran Republican operative based in Florida.